Commerce: The country's fishing industry revised its netting procedures only to be told it remains out of compliance, keeping the lucrative U.S. market off limits.

MANZANILLO, Mexico — Tuna boat owner Antonio Suarez thought earlier this year that his long and agonizing wait was over. The lifting of the U.S. embargo on tuna from Mexico was in sight, meaning his four boats could catch and sell "dolphin-safe" tuna to the lucrative American market that has been shut off to him for the last decade.

He invested $6 million last year in new canning machinery and a refrigerated storehouse here at his Grupomar tuna fishing and processing operation, anticipating the thousands of tons of additional yellowfin tuna he'd be catching and canning for the U.S. market this year.

But Suarez's hopes were dashed--and a new controversy hatched--when a federal judge in San Francisco ruled in March, just as the embargo ended, that Mexican tuna didn't deserve the critical "dolphin-safe" label. That made the embargo's end a meaningless event, because without the label, tuna from Mexico or any other country is unmarketable to U.S. consumers.

The ruling has done more than frustrate Suarez and deal another body blow to the $150-million Mexican fishing industry, once a world leader that has shrunk by half since 1990, losing 4,000 jobs. It illustrates how U.S. trade policy and court decisions can have severe but little-noticed effects on poor countries, actions that sometimes are based on bitterly disputed science.

Now the Mexicans are threatening to abandon the dolphin-protective fishing methods they adopted in 1990 as part of its so-far unsuccessful campaign to reenter the U.S. market. That could reverse much of the gains made in dolphin protection over the last decade, and deplete tuna stocks at a faster rate over the long term, some environmentalists maintain.

"What are we getting in return? Nothing," said Alfonso Rosinol, executive director of Mexico City-based fishing trade association CANAINPESCA, of his industry's participation in an internationally sanctioned dolphin-protection program.

Mexico is a tuna fisher's paradise. Migratory patterns make its 200-mile territorial seas a prime fishing ground for yellowfin, the largest and most marketable tuna variety. Big commercial boats use mile-long purse-seine nets to encircle entire schools of yellowfin tuna that, for obscure reasons, swim under pods of dolphins in the Eastern Pacific.

But the purse-seining method used by the Mexican, U.S. and other tuna boats was drowning or fatally injuring 130,000 dolphins a year by the late 1980s. In response to a grass-roots campaign launched by consumers horrified by video footage of dying "Flippers," Congress in 1990 embargoed all tuna caught by purse seiners that fished under dolphins.

While most U.S. boats simply left for new bases of operation in the Western Pacific, the Mexican tuna fleet tried to make purse-seining safer for dolphins, succeeding to a remarkable degree. By eliminating certain net maneuvers, night fishing and by standardizing aggressive rescue efforts, Mexico and other countries reduced dolphin kills in the Eastern Pacific to 1,400 last year.

At the same time, Mexico lobbied for a change in the law, which it got with the modified Marine Mammal Protection Act in 1997 after persuading Congress that dolphin kills had declined to statistically insignificant numbers.

Congress also made a crucial change in the dolphin-safe definition, allowing individual catches to qualify for the labeling as long as they were segregated in tuna boat "wells" from catches in which dolphins died, and as long as a nation's fleet kept overall kills to a prescribed minimum.

Finally, the embargo was set to be lifted this spring, an action that received a green light not only from the U.S. National Marine Fisheries Service, but environmental groups including Greenpeace, the World Wildlife Fund and the Center for Marine Conservation.

"Mortality of dolphins in the Eastern Pacific has declined precipitously," said Scott Burns of the World Wildlife Fund in Washington. "It makes sense to recognize that progress." Said the Center for Marine Conservation's Nina Young: "As long as Mexico abides by the law, we felt a dolphin-safe designation was the reward for compliance."

In making his ruling, U.S. District Judge Thelton Henderson upheld the contention of Earth Island Institute, a San Francisco environmental group, that the U.S. government hadn't sufficiently studied the troubling fact that despite safer fishing methods, global dolphin stocks barely grew, if at all, in the 1990s.

Earth Island contends that Mexican fishermen may be indirectly causing dolphins to die from "stress" after having been set free from the purse seiner nets, and therefore their tuna does not merit the seal.

"You cannot chase and harass and encircle dolphins and call the method dolphin-safe," said Earth Island Institute spokesman Mark Berman. "In the long run, the dolphins can die from pneumonia, the calves get separated from their mothers and die within a few days because they don't feed. In the end, [purse-seining] is a death sentence."